Follow-up to: Boring Advice Repository
Many practical problems in instrumental rationality appear to be wide open. Two I've been annoyed by recently are "what should I eat?" and "how should I exercise?" However, some appear to be more or less solved. For example, various mnemonic techniques like memory palaces, along with spaced repetition, seem to more or less solve the problem of memorization.
I would like people to use this thread to post other examples of solved problems in instrumental rationality. I'm pretty sure you all collectively know good examples; there's a comment I can't find from a user who said something like "taking a flattering photograph of yourself is a solved problem," and it's likely that there are other useful examples like this that aren't common knowledge. Err on the side of posting solutions which may not be universal but are still likely to be helpful to many people.
(This thread is allowed to not be boring! Go wild!)
Just doing intermittent fasting by itself didn't do much for me, but doing intermittent fasting where I also measured and reduced calorie intake allowed me to lose 15 pounds (from 185 to 170). The LeanGains website was really helpful. It's also worth noting that prior to starting this, I already had a relatively healthy diet and exercised regularly.
That being said, even the guy who made LeanGains doesn't claim it will work for everyone. But for the first month I did it I screwed it up (by not also restricting calorie intake) and saw no change, then after fixing that I lost about a pound a week.